How to Change or remove hex decimal color in photo?

How can I change a color to be a different color or just remove the color to see another photo under the image only where the hexadecimal color is? For instance in this photo that has blue leaves around the poetry in different colors how can I change the blue to be different colored leaves or just remove the color all together so do can see a different image underneath? Do I need the hexadecimal color - 0174B8?